DBU‐Promoted Nucleophilic Activation of Carbonic Acid Diesters

Carafa, Marianna; Mesto, Ernesto; Quaranta, Eugenio

doi:10.1002/ejoc.201001725

Cited by 54 publications

(65 citation statements)

References 59 publications

(24 reference statements)

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“…It has been, in fact, reported that organic carbonates are activated by DBU via formation of an N -alkoxycarbonyl DBU derivative [67–71]. However, in this case study, DBU most probably promotes the formation of the methoxycarbonyl reaction intermediate, as well as the intramolecular cyclisation reaction (B Al 2 mechanism).…”

Section: Reviewmentioning

confidence: 75%

Isosorbide and dimethyl carbonate: a green match

Aricò

Tundo

2016

Beilstein J. Org. Chem.

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In this review the reactivity of the bio-based platform compounds D-sorbitol and isosorbide with green reagents and solvent dimethyl carbonate (DMC) is reported. Dehydration of D-sorbitol via DMC in the presence of catalytic amounts of base is an efficient and viable process for the preparation of the industrially relevant anhydro sugar isosorbide. This procedure is “chlorine-free”, one-pot, environmental friendly and high yielding. The reactivity of isosorbide with DMC is equally interesting as it can lead to the formation of dicarboxymethyl isosorbide, a potential monomer for isosorbide-based polycarbonate, and dimethyl isosorbide, a high boiling green solvent. The peculiar reactivity of isosorbide and the non-toxic properties of DMC represent indeed a green match leading to several industrial appealing potential applications.

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Section: Reviewmentioning

confidence: 75%

Isosorbide and dimethyl carbonate: a green match

Aricò

Tundo

2016

Beilstein J. Org. Chem.

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“…Inspired by these works, we decided to explore the possibility of replacing the acyl halide, which is toxic and unstable, with 1-benzoylimidazole as the benzoylation reagent with 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU) as the catalyst. DBU is often used as a organobase catalyst in many base-catalyzed reactions [47][48][49][50], having been recognized as an excellent nucleophilic catalyst, leading to rapid and efficient acetylation of non-nucleophilic azacycles, such as indoles, pyrroles, and oxazolidinones. D-pyranosides.…”

Section: Resultsmentioning

confidence: 99%

Regioselective Benzoylation of Diols and Carbohydrates by Catalytic Amounts of Organobase

Hou

Ren

et al. 2016

Molecules

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Abstract:A novel metal-free organobase-catalyzed regioselective benzoylation of diols and carbohydrates has been developed. Treatment of diol and carbohydrate substrates with 1.1 equiv. of 1-benzoylimidazole and 0.2 equiv. of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in MeCN under mild conditions resulted in highly regioselective benzoylation for the primary hydroxyl group. Importantly, compared to most commonly used protecting bulky groups for primary hydroxyl groups, the benzoyl protective group offers a new protection strategy.

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“…7, 11 Shieh’s work led Carafa and colleagues to shore up DBU’s catalytic nature in 2011, in which they isolated the unprecedented ketene aminal. 12 Carafa’s findings significantly influenced the proposed reaction scheme in this work; specifically, it was their isolation of the ketene aminal species and their emphasis on the ketene aminal as the key intermediate in acylation reactions. In 2012, Waymouth/Hedrick et al showed the potential for DBU to catalyze the polymerization of lactide in the absence of an alcohol macro-initiator involving a hypothesized zwitterionic ROP (ZROP) mechanism.…”

Section: Introductionmentioning

confidence: 92%

Elucidating a Unified Mechanistic Scheme for the DBU-Catalyzed Ring-Opening Polymerization of Lactide to Poly(lactic acid)

2016

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The synthesis of poly(lactic acid), PLA, is facile in the presence of the cyclic, organic amidine catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene, DBU. Since DBU’s catalytic capability was first reported by Lohmeijer and colleagues in 2006 for ring-opening polymerizations (ROP), there have been numerous studies conducted by a variety of groups on the catalytic functioning of DBU in the ROPs of cyclic esters resulting in a large body of un-unified material from a mechanistic standpoint. This lack of clarity will hamper engineering polymers with desired characteristics from cyclic ester and lactone monomers. The work outlined in this paper seeks to propose a unified picture of the mechanisms in the DBU catalyzed ROP of lactide. In providing this unified picture of the ROP our work encompassed: (i) proposing a detailed reaction network scheme, (ii) conducting syntheses of lactide and DBU over a range of initial concentrations, and (iii) kinetic modeling to further support the proposed reaction network. As a result, our work has produced: (i) kinetic data, (ii) a consistent, viable reaction scheme verified through kinetic modeling, (iii) deduced and quantified the interplay between polymerization routes facilitated by the presence of DBU, thus demonstrating the need for detailed kinetic studies to deconstruct complex reaction networks, (iv) the first experimental evidence in support of the combination of ketene aminal-ended chains with alcohol-ended chains, and (v) analyzed the robustness of the catalyst to acid contamination.

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DBU‐Promoted Nucleophilic Activation of Carbonic Acid Diesters

Cited by 54 publications

References 59 publications

Isosorbide and dimethyl carbonate: a green match

Isosorbide and dimethyl carbonate: a green match

Regioselective Benzoylation of Diols and Carbohydrates by Catalytic Amounts of Organobase

Elucidating a Unified Mechanistic Scheme for the DBU-Catalyzed Ring-Opening Polymerization of Lactide to Poly(lactic acid)

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